Originally Posted by
JeCCo
If the flight is sold out / lacking space you could still guarantee into a higher fare class (M, L, etc) it just wont be as cheap.
CX will guarantee even if "sold out". I believe what
Wasabi Tofu meant is that seat guarantee cannot work for a subclass that is "not sold", i.e., if CX does not even provide a fare for subclass V, the member cannot do seat guarantee on "V" for that flight.
That happens many years ago on SFO-HKG route. L & V are sometimes available as promotions and I was only able to ticket in M if L & V are "unbookable".